Best way to perform a "restoration charge" on my van "house" Firefly G31 battery?

[brewera]

I have a small van that I installed a single 116Ah Firefly G31 battery ([https://fireflyenergy.com/oasis-mcf-g31.html](https://fireflyenergy.com/oasis-mcf-g31.html)) in for my camping adventures. I charge the battery with a Kisae DMT1250 MPPT charger ( [DMT1250 – Kisae Technology Inc (kisaepower.com)](https://www.kisaepower.com/products/dmt1250/) ) via DC to DC or the single 100 watt solar panel on the roof. I currently do not have any method to shore charge. It has been working great for about seven months and now lately I am not getting as long of run times for my minimal usage. I then found in the Firefly manual that I should occasionally perform a "restoration charge" on the battery. The procedure they state is:





As stated, Firefly Batteries can operate in a partial state of charge for long periods of time without sustaining any permanent damage. The usable capacity will decrease, however, with each cycle within a partial state of charge, up to a point. In order to regain the full original capacity and in some cases more, it is necessary to perform a restoration charge. To perform the restoration charge: charge the G31 to 14.4V and continue to charge until the current drops to 0.5 A on the G31 and apply a float charge of 13.5V for 24 hours. Fully discharge the battery to 10.5V, and then repeat the same charge cycle.



What would you all recommend would be the best way to accomplish this procedure? I own a couple of multimeters. Do I need to buy special equipment? Do I need to take the battery out of the van? I am looking for some creative solutions.

 

[MiSh]

The easiest way to accomplish this is to buy a small programmable battery charger like a Victron and be done with it. But you're stating you have no access to plug anything into a 120v wall outlet? Obviously, the other option is to charge the battery by your solar and/or running the van to keep the charger going. According to your CC manual it can be set to the required 14.4v.

 

[Substrate]

Sadly, there's no way to do this *accurately* unless you have a reliable ac-source.

The only hope is to wing-it if you like. That would involve using your SCC (you didn't mention that you even have one!)

Set your SCC to 14.4v. To stay there, disable any timers. If you can't disable the timers, and it drops to float to soon, you can cheat by setting the float-voltage to the same 14.4v.

During the day, watch your SCC's current measurement to see if it has tailed off to 0.5A, AND that you measure 14.4v on the battery terminals. This could take a few days.

Half-way done.

Now, in your SCC, program the CV/Absorb/boost (whatever they want to call it) to a very low voltage like 13.5v. Set your float voltage to the same 13.5v.

Let it charge like this for a few days.

Repeat this whole process by discharging down to 10.5v and do this again.

One thing not mentioned in your post is if Firefly has indicated that there is any minimum current necessary for this. Hence using variable solar, may make this troublesome.

Practically, the best thing you can do at this point is to just stay in absorb to 14.4v as long as you can (disabling float, or cheating by changing the value to the same), until current drops to 0.5A or below.

Because this is van-life, I'm assuming a daily-cyclic routine. If so, then just stay in 14.4v absorb (and cheating float by using the same 14.4v value if necessary). The sun will prevent this from being damaging, as it would be if using a 24/7 ac, or weekend-warrior kind of duty. Daily cyclers have it easy! BULK=ABSORB=FLOAT. (like 14.4v)

 

[Substrate]

GEEZ - I bored *myself* after reading that.

1) Use your dc-dc charger to charge up

2) Because you are a daily-cycler, set *both* your CV/ABSORB/BOOST (whatever they decide to call it) in your SCC controller to 14.4v. Set float to 14.4v also. This defeats any "drop to float" timer.

3) Run like this from now on with solar. Daily cycling gives you license to do this. The sun sets to prevent this from long-term damage.

If you aren't daily cycling for some reason later, then drop your float back to the norm voltage that Firefly calls for.

 

[brewera]

The easiest way to accomplish this is to buy a small programmable battery charger like a Victron and be done with it. But you're stating you have no access to plug anything into a 120v wall outlet? Obviously, the other option is to charge the battery by your solar and/or running the van to keep the charger going. According to your CC manual it can be set to the required 14.4v.

I have no problem buying a small charger and every once in a while use it to accomplish the task if this is what I need to do until I decide to move on to another battery technology. You mention a Victron charger. Do you have a recommended model?

 

[brewera]

GEEZ - I bored *myself* after reading that.

1) Use your dc-dc charger to charge up

2) Because you are a daily-cycler, set *both* your CV/ABSORB/BOOST (whatever they decide to call it) in your SCC controller to 14.4v. Set float to 14.4v also. This defeats any "drop to float" timer.

3) Run like this from now on with solar. Daily cycling gives you license to do this. The sun sets to prevent this from long-term damage.

If you aren't daily cycling for some reason later, then drop your float back to the norm voltage that Firefly calls for.

I appreciate both the posts! I will look into adjusting my MPPT charger to accomplish what you recommend. As I asked Mik4111, if you have a recommended small AC charger I should purchase that would be super helpful. I don't mind using it to keep this battery optimal until I eventually move on to another battery technology.

 

[MiSh]

I have no problem buying a small charger and every once in a while use it to accomplish the task if this is what I need to do until I decide to move on to another battery technology. You mention a Victron charger. Do you have a recommended model?

The Victron 12v Smart charger works really well and has a ton of features. You can access all the settings thru your cell phone using Bluetooth. I own two of them in different voltages.

https://www.amazon.com/Victron-Ener...hvlocphy=&hvtargid=pla-4584070153365592&psc=1

 

[Substrate]

Ah, I was under the impression you had no AC available.

Use the Victron or other capable charger. Do not skimp on the required amount of float time, because if the Victron or any other charger you use may not be watching for CV/absorb tail-current dropoff to 0.5A, but instead applies a timeout prematurely before reaching this, you'll need to compensate with much more float - say 48 hours.

That is, if you are still interested in trying to follow the refresher guidelines by Firefly. Ideally done with a programmable charger (bench supply - but one has to know how to use it so you don't bork the batt!)

Discharge to 10.5v as per Firefly, and charge back up - perhaps with the Victron. Measure your capacity with another discharge to 10.5v and see if it improves. If there is no improvement, *maybe* just one more cycle of this (with 48 hours of float!) to detect improvement, but you don't want to test too much with lead-acid.

 

[Michael]

What did you finally do to solve your problem? Do you have a report for us?